致命错误：xmlrpc_encode_request（）：XML-RPC不支持ripcord_client.php

Question

我已经使用PHP5-xmlrpc创建了一个应用，我正在使用ripcord连接到我的Odoo webservice。
它与php5一起工作正常，但自从我更新到php7后，会发生以下情况：

$common = ripcord::client(ODOO_URL . "/xmlrpc/2/common") //create a connection
$uid = $common->authenticate(ODOO_DB, $user, $pass, []); //this call fails

我得到的错误是Fatal error: xmlrpc_encode_request(): XML-RPC doesn't support circular references in [PATH]/ripcord_client.php on line 226

此行为$request = xmlrpc_encode_request( $name, $args, $this->_outputOptions );，值为：

$name => 'authenticate'  
$args => Array (
            [0] => [db_name]
            [1] => [login]
            [2] => [password]
            [3] => Array ()
         )

$this->_outputOptions => Array (
            [output_type] => xml
            [verbosity] => pretty
            [escaping] => Array (
                    [0] => markup
                )
            [version] => xmlrpc
            [encoding] => utf-8
        )

一些建议将不胜感激。